The invention pertains to a connector element for tubing or hoses of elastically expandable material with a tubular part of inelastic material that can be inserted in a tightly sealed manner into a tubing or hose end and that has a so-called pine-cone or thorn profile.
Connector or coupling elements with such insertion ends are already known in a variety of forms. They are used with tubing and hose lines that are designed for water or other fluids with at most a few bar of positive pressure with respect to ambient pressure. The pine-cone or thorn profiles formed on the tubular part are intended to guarantee that tubing or hose ends can be connected in a tightly sealed manner to the connector element without additional fastening parts, a friction and form-fit connection generally being produced, in which the tubing or hose end is slightly expanded and exerts radially inward-directed restoring forces, while the sharp edges of the pine-cone or thorn profile made of inelastic material dig into the inside wall of the tubing or hose end-like barbs.
It ought to be immediately obvious that the success of such a combined insertion connection depends to quite a considerable extent on the manufacturing tolerances of the components involved and on their material properties. In order to improve the sealing of such insertion connections, it has already been proposed to provide a circular section on the front end of the tubular part and to form a circumferential groove therein for an O-ring. In this way, the sealing effect could be improved. It has turned out, however, that an improved sealing effect can be achieved only if the insertion of the tubular part into the tubing or hose end is done with great care; because, otherwise, the O-ring is pressed out of the groove or twisted about itself to a differing extend across its circumference whereby its sealing effect is lost. Due to the tight matching with the circular area on the inner diameter of the tubing or hose end, considerable shearing forces on the O-ring arise during insertion, which moreover are dependent on the surface roughness of the inside wall of the tubing or hose end, so that displacement or damaging of the O-ring cannot be reliably avoided even with careful handling.
The invention is based on the problem of avoiding the aforementioned disadvantages in a connector element of the type mentioned initially and forming the insertable tubular part such that a reliable sealing of the insertion connection is achieved and displacement or damaging of the sealing element can be avoided.